Bottom frame rail size? Will 2" x 4" be enough?

[DavidReaves]

So I'm planning a chicken tractor, still. It will have a reach-in coop, 4'x4' with an eggsternal nesting box. (I couldn't resist). Most of the construction will be 2"x 2" framing for weight and cost. The floor will be treated 3/4" plywood with a piece of vinyl roll overlaid. The sides are of 3/8" plywood sheathing, again for weight and cost. The roof will be opaque polycarbonate panels for weight and strength (unfortunately, not cost). There is an attached run that is framed every two feet, also of 2" x 2" and will frame all four sides, connecting to the frame top and bottom. The run section will also have a polycarbonate panel roof. The run and the area below the coop will be covered with 1" x 1/2" welded wire.

So, with that as the background, will the 12 foot 2"x 4"s be strong enough to serve as the bottom frame? I don't expect it will be a problem other than potentially when the tractor is moved. When moving, I plan to use retractable 10" pneumatic tires under the edge of the coop, where the run attaches. So, the 12' 2 x 4 will be loaded with about 150(?) pounds including plywood, framing, roofing, wire, and paint. Most of that will be in the 4 feet behind the wheel, though some will be in the other 8 feet forward of the wheel.

What do you think?

 

[cavemanrich]

Strong enough in my view. Make sure you have it the vertical position. Another thing to consider,,, is the quality of that individual 2 x 4 . Choose one that has minimal knots, and the grain is somewhat straight to the length. Of course no piece of wood is going to be perfect,,, but choose the best out of the pile.

 

[DavidReaves]

Strong enough in my view. Make sure you have it the vertical position. Another thing to consider,,, is the quality of that individual 2 x 4 . Choose one that has minimal knots, and the grain is somewhat straight to the length. Of course no piece of wood is going to be perfect,,, but choose the best out of the pile.

Luckily, they didn't have ANY 12' boards. Since I also needed 2 four-foot sections for the ends, I was able to have them cut 16' boards. Unlike the shorter boards, the 16s were beautiful straight grain with no knots! They should be fairly strong.

If y'all end up telling me that they're not strong enough, I will go back for 2" x 6", but I'm hopeful that they will work, since they will be lighter and easier to move (and that money is already spent).

 

[DavidReaves]

I went with the 4" frame. Since the sidewalls were built as a module, the bottom of the sidewall frame adds extra thickness to the 2" x 4" to make what is effectively a laminated 2" x 6" beam. You can see that in the attached photo. The front section which you can also see will have a section of plywood between the two 2" x 4"s to serve as cross-bracing for side-to-side strength on the front of the frame. The back of the run will be secured to the coop module for rigidity.

Here's a link to the post where I describe the start of the chicken tractor build. I'll update it as I progress with the build.

New Covered Chicken Tractor Started

Thanks!

 

[DavidReaves]

Here's a photo that shows the front plywood bracing. The frame is rock-solid on that end.